A bite registration device is used to obtain a model of the registration of an individual's dental arches for laboratory use in fabricating an appliance for treating the individual. Historically, bite registrations have been obtained by using wax. The wax is shaped to conform to the general arch shape, and then placed intra-orally between the individual's upper and lower dental arches. The individual is instructed to bite into the wax. The bite creates arch impressions in the wax that provide the registration of one arch to the other. The impression-containing wax is later used in conjunction with other dental equipment, such as dental casts and an articulator, to fabricate an appliance that will have the proper fit for the individual's bite.
While wax has enjoyed long-standing usage for bite registration, it is not without problems. It may warp, bend, and/or become brittle, depending on how it is handled, stored, and used. If these, or other similar, occurrences happen to the wax before it has served its intended purpose, treatment of the individual may be compromised or complicated.
It has also been proposed to obtain bite registration concurrent with obtaining full dental arch impressions. An example of a device that is used for that purpose is described in U.S. Pat. No. 3,302,289. One potential disadvantage of simultaneously obtaining full dental arch impressions and bite registration in a single device is that subsequent use of the resulting model may be compromised. It is believed that fabrication of an appliance for an individual is facilitated, and the appliance is apt to have a better fit, if bite registration is obtained separately from full dental arch impressions.
The present invention relates to a new and unique bite registration device that offers significant benefit over prior devices, especially wax bite registrations. The bite registration device of the present invention retains an accurate registration that remains dimensionally stable under normal usage, yet possesses a certain limited resilient flexibility. This flexibility is beneficial because it allows the device to be peeled from an arch to which it may adhere after having been bitten on by an individual, and also to be readily peeled from a dental cast. While care must of course be prudently exercised in handling and using the device, it is believed that the device is more tolerant to handling than prior bite registration devices.
The device of the present invention has the further advantage that its occlusal wall can be made relatively thin. This is important because it allows the individual to more closely approach full closure of the arches when biting into the device. The closer that the bite is to full closure, the better the result obtained.
A further aspect of the invention relates to the use of polymer and/or copolymer materials in the fabrication of the bite registration device. While certain principles of the invention do not depend specifically on the materials used, preferred materials include various durometers of ethylene vinyl acetate. These preferred materials provide important benefits. One important benefit is that a bite registration device according to the invention can be made by injection molding. It is hygenically manufactured and hermetically sealed until ready to be used by a dentist or orthodontist. For use, it is heated to slightly soften the material, and then placed between dental arches and bitten on by the individual. It is allowed to cool to stabilize the registration, and thereafter removed from the mouth. It then becomes available for use as needed in the course of procedures for fabricating an appliance, or other device, for the individual.
The device possesses certain constructional features that have significance in injection molding processes for fabricating the device. One constructional feature involves a series of small holes in certain lamina of the device. These holes are the result of using stand-off pins to hold another lamina in the mold cavity of an injection mold while the injected material is being forced into the cavity onto the held lamina. This aspect of using stand-off pins is described in more detail in my co-pending patent application relating to Dental Arch Appliances, Ser. No. 07/801,673, filed Dec. 2, 1991. Another constructional feature relates to the inclusion of V-shaped notches in the held lamina. These notches have been found to improve the flow of the material being molded onto the held lamina such that the proper lamination result is obtained.
While the use of ethylene vinyl acetate is not broadly new in intra-oral devices, it appears that its use has not heretofore been proposed for a bite registration device. Perhaps this is because of a desire that a bite registration device have a relatively thin occlusal wall. According to certain principles of the invention, a bite registration device having a relatively thin occlusal wall, not greater than 0.100 inch thick, is provided by multi-laminar ethylene vinyl acetate wherein one lamina has a durometer different from that of another. While the thickness of an occlusal wall cannot be so small that a bite results in excessive bite-through, a minor amount of bite-through that does not destroy the general integrity of the registration is not considered objectionable in most instances. In one specific embodiment of device to be described herein, one lamina has a durometer and a thickness that provide a majority of the resistance to bite-through, but in doing so takes an impression of only the cusps and tips of teeth of the arch impressed into it while Ether, softer lamina takes a deeper impression of teeth of the other arch. This specific embodiment is entirely acceptable even though it has such a relatively thin occlusal wall. Another specific embodiment of device to be described herein comprises two relatively softer lamina on opposite sides of a relatively harder intermediate lamina. This other embodiment provides deeper arch impressions than the first embodiment, but it has an occlusal wall whose thickness is greater. The first embodiment may be preferred by orthodontists and dentists in some instances while the second may be preferred in others.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which are accompanied by drawings. The drawings disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.